For large reptiles and tortoises, the Zoo Med Repti-Therm Habitat Heater is your best bet to keep your pet warm and safe. It's an 18" x 18" industrial strength heater with a ton of great features.
Features:
Automatic protection thermostat shuts off the heater at 119°F (48°C) to prevent overheating.
LED power indicator tells you when the heater is on.
Large, Rugged 18" x 18" Heat Mat.
120 Volts, 40 Watts - 75-80% electrical savings over other heating devices.
Mounting rails allow for secure placement on the floor or side of your enclosure.
Made from Water resistant, easy-to-clean, moisture proof high-density polyethylene plastic.